SMM memory size was determined by the MCH part, not ICH. The boards we hadwith i82801dx used ASEG with 128 kiB of SMRAM. The only remaining user ofi82801dx couples with e7505 that could handle 1 MiB of TSEG.

Post by ron minnichI'm looking for a mainboard emulation which can support the larger sizes,e.g. 8M.

Out of the box, not supported. But emulation/qemu-q35 can do that if youadd "select SMM_TSEG" and some glue logic to write those TSEG relatedregisters. You also need a recent QEMU, 2.10 or later.